View angle has become one of the major parameters to be improved for current display device technologies. For example, In-Plane Switching (IPS) technology and Multi-domain Display (MD) technology are adopted to expand a view angle of a display device. Existing wide-angle liquid crystal display (LCD) devices usually have a relatively broader view angle which allows contents displayed on the LCD being clearly observed within a range of about 178°.
However, under certain specific circumstances such as subway, bus and elevator, users may not expect the contents displayed on his/her display device to be observed by other people for consideration of privacy, especially when a wide-angle display that involves matter of privacy is used. Furthermore, it's usually very difficult for some well-known display devices such as mobile phone to adjust the view angle thereof by mechanical means due to integral design requirements for portability.